A newly developed coaxial superelastic nickel-titanium(NiTi) archwires help to produce better tooth movements in comparison of single-strand superelastic NiTi, as per the recent study published in “The Cochrane Database of Systematic Reviews” journal.

The first archwires introduced in the orthodontic treatment to correct teeth alignment by rectifying crowding and rotations were the initial arch wires. Due to the number of alternatives of orthodontic archwires, the choice of the most efficient wire that cause less pain and root reabsorption along with tooth movement at the beginning aligning phase of the treatment is crucial.

Therefore, Yan Wang and colleagues analyzed the consequences of various archwires to align teeth with fixed orthodontic braces. The study was an update of a review that published in 2010 " entitledInitial archwires for alignment of crooked teeth with fixed orthodontic braces". The Medline Cochrane Central Register of Controlled Trials (CENTRAL), Ovid, World Health Organization International Clinical Trials Registry Platform, US National Institutes of Health Trials Registry and Embase Ovid searched to extract study-related databases. During database search, no restriction on publication date or mode of language. Randomised controlled trials (RCTs) with full arch, upper/lower or both fixed orthodontic instruments were involved in the trial. The data extraction, study selection and risk of bias evaluation were done via two review authors. The disagreements were resolved through discussion. Missing information was obtained through the corresponding authors. The quality of evidence of each comparison assessed as per GRADE criteria and ranked as very low, low, medium or high. 

A total of 12 RCTs (3 new RCTs with 228 patients) with 799 patients were analyzed. Out of 12 RCTs, six were unclear; three were at high risk and three at low risk of bias. No root reabsorption related adverse outcomes were noticed. The trial comprised an evaluation of six comparisons - 

Superelastic NiTi versus Multistrand stainless steel archwires

The comparison included five studies with insufficient evidence related to dissimilarity in the alignment rate between the groups (low-quality evidence). The VAS score finding also indicated no significant difference between these two approaches on day 1(moderate-quality evidence). Appropriate for meta-analysis. 

Thermoelastic NiTi versus Multistrand stainless steel archwires

The comparison involved two studies, but the data was not appropriate for meta-analysis. This group also exhibited low-quality evidence regarding alignment rate among the groups. No pain measurement was done. 

Superelastic NiTi versus Conventional NiTi archwires

A total of three studies were evaluated, but the data was not appropriate for meta-analysis. Group comparison exhibited very low to low-quality evidence with regards to either pain or alignment. 

Thermoelastic NiTi versus Conventional NiTi archwires

A total of two studies were evaluated, but the data was not appropriate for meta-analysis. Low-quality evidence was present regarding alignment rate. No pain measurement was done. 

Coaxial superelastic NiTi versus Single-strand superelastic NiTi archwires

There was only one study with moderate-quality evidence that coaxial superelastic NiTi can generate higher tooth movement over 12 weeks as compared to other modality. No pain measurement was done. 

Thermoelastic NiTi versus Superelastic NiTi 

A total of three studies were found with low-quality evidence for alignment rate.

As per the analysis, no high-quality evidence was noticed. Moderate-quality evidence was seen by coaxial superelastic nickel-titanium(NiTi) archwires for better tooth movement and by comparison group "Superelastic NiTi versus Multistrand stainless steel archwires" which shows no difference in pain scores at day one. Expect these findings; only insufficient data were obtained with other archwires comparison groups.